The water in pools and spas must be treated in order to prevent growth of algae or bacteria that may flourish in large bodies of untreated water. Many pools and spas are treated by traditional chlorination sanitation—direct addition of chlorine to the water. However, more and more pools and spas are being installed or retrofitted with salt water chlorinators. Salt water chlorinators use dissolved salt (NaCl) as a store for the chlorination system. The chlorinator uses electrolysis to break down the salt into its individual elements, one of which is chlorine. The resulting chemical reaction eventually produces hypochlorous acid (HClO), and sodium hypochlorite (NaClO), which are the sanitizing agents already commonly used in swimming pools. As such, a saltwater chlorination system utilizes a chlorine generator instead of direct addition of chlorine.
One of the benefits of a salt chlorination system in a pool or spa is the convenient and constant delivery of pure chlorine-based sanitizer. Such systems help eliminate chloramines, which are the irritants that give traditional pools their caustic smell and can cause burning eyes for swimmers. Salt chlorination systems use electrolysis, which burns off the chloramines in the same manner as traditional shock (oxidizer) and reduces dissolved alkali minerals in the water. However, there are also some disadvantages to the use of salt water chlorination systems, one of which is that salt conducts electricity, which can cause galvanic corrosion.
When salt is in the presence of two dissimilar metals, it can turn the system into a battery of sorts, with one of the electrodes giving off an electron which creates corrosion. This corrosion increases when there is liquid in the “battery,” such that adding salt to a pool system creates an electrolyte of sorts (e.g., when the salt is dissolved in a solvent (e.g. water), it becomes an electrolyte with free ions). This corrosion can damage some metals, as well as stone or other pool decking materials. Many pool equipment manufacturers will not warranty stainless steel products damaged by saline pools.
There is thus a need to provide protective features for various components to be used in connection with salt water pools, particularly those components that come into contact with the water on a recurring basis. For example, some mechanical systems that may be used in connection with pools and spas are pool cover systems, which can be activated to roll a cover across a pool or spa surface for protection, money savings, and/or safety reasons. Pool covers can save pool owners money by saving on heat, chemicals, equipment and pool cleaning, and other operating costs; they can save lives by providing a safeguard against accidental pool entry by an unattended child; they can save time by keeping dirt, leaves and other debris out of the pool when the pool is covered; and they can save energy by reducing heating costs. However, if the pool cover extension and retraction system components become corroded, this can damage the ability of the system to work properly. Accordingly, improvements to pool cover assembly components are needed in order to help ensure that they remain corrosion-free, even when used in connection with a salt water pool.